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Technical Paper

Fatal and Severe Injuries in Rear Impact; Seat Stiffness in Recent Field Accident Data

2008-04-14
2008-01-0193
A decade ago, James, et.al. published a detailed study of the available NASS data on severe rear impacts, with findings that “… stiffened or rigid seat backs will not substantially mitigate severe and fatal injuries in rear impacts.” No field accident study has since been advanced which refutes this finding. Advocates of rigidized seat backs often point to specific cases of severe rear impacts in which MAIS 4+ injuries are associated with seat back deformation, coupled with arguments supporting stiffer seatback designs. These arguments are generally based upon laboratory experiments with dummies in normal seating positions. Recent field accident data shows that generally, in collisions where the majority of societal harm is created, yielding seats continue to provide benefits, including those associated with whiplash associated disorders (WAD).
Technical Paper

Performance of Rear Seat Belt Restraints

2003-03-03
2003-01-0155
Field experience has consistently indicated that lap-only belts and lap-shoulder belts perform well and about equally in prevention of fatalities and serious injuries in the rear seating positions. Analyses based on overall usage and injury figures from the Fatal Analysis Reporting System (FARS), double-pair analysis of FARS data, and still older data bases have shown that, in the rear outboard seating positions, injury rates are about the same for lap-only and lap-shoulder belted crash occupants. Although sparse, recently available field data from the 1988-2001 National Analysis Sampling System / Crashworthiness Data System (NASS/CDS) files confirm the finding that, when used by rear seat occupants, lap-only belts perform about equally with lap-shoulder belts as countermeasures for serious and fatal injury in severe frontal crashes.
Technical Paper

Force/Deflection and Fracture Characteristics of the Temporo-parietal Region of the Human Head

1991-10-01
912907
Impact tests were conducted on thirty-one unembalmed human cadaver heads. Impacts were delivered to the temporo-parietal region of fixed cadavers by two, different sized, flat-rigid impactors. Yield fracture force and stiffness data for this region of the head are presented. Impactor surfaces consisted of a 5 cm2 circular plate and a 52 cm2 rectangular plate. The average stiffness value observed using the circular impactor was 1800 N/mm, with an average bone-fracture-force level of 5000 N. Skull stiffness for the rectangular impactor was 4200 N/mm, and the average fracture-force level was 12,500 N.
Technical Paper

Crash Protection in Near-Side Impact - Advantages of a Supplemental Inflatable Restraint

1989-02-01
890602
Collision Safety Engineering, Inc. (CSE), has developed a test prototype system to protect occupants during lateral impacts. It is an inflatable system that offers the potential of improved protection from thoracic, abdominal and pelvic injury by moving an impact pad into the occupant early in the crash. Further, it shows promise for head and neck protection by deployment of a headbag that covers the major target areas of B-pillar, window space, and roofrail before head impact. Preliminary static and full-scale crash tests suggest the possibility of injury reduction in many real-world crashes, although much development work remains before the production viability of this concept can be established. A description of the system and its preliminary testing is preceded by an overview of side impact injury and comments on the recent NHTSA Rule Making notices dealing with side-impact injury.
Technical Paper

Facial Impact Response — A Comparison of the Hybrid III Dummy and Human Cadaver

1988-10-01
881719
Results indicate the need for a redesigned Hybrid III face capable of accurate force and acceleration measurements. New instrumentation and methods for facial fracture detection were developed, including the application of acoustic emissions. Force/ deflection information for the human cadaver head and the Hybrid III ATD were generated for the frontal, zygomatic, and maxillary regions.
Technical Paper

A Load Sensing Face Form for Automotive Collision Crash Dummy Instrumentation

1986-02-24
860197
This paper summarizes the development of an Instrumented faceform which can record time histories of impact-related pressures at fifty-two locations over the entire face of a Hybrid 2 crash dummy skull. Pressures are measured by using piezo-electric, thin-plastic films; a high-speed, multiplex data acquisition system; signal conditioning; a software-controlled computerized data reduction and recording scheme; and a submergence calibration technique. The construction of the modified dummy face and the calibration gear are discussed. Examples of preliminary laboratory impact test results are presented. Theory and techniques relating to signal processing software, microprocessor controlled random-access-memory data-retrieval system and system calibration are also discussed. It is hoped that this tool, now undergoing final development and verification testing, will find extensive use in the evaluation and safety-related design of vehicle interiors and occupant restraints.
Technical Paper

A Repeated-Crash Test Technique for Assessment of Structural Impact Behavior

1986-02-24
860208
An economical alternative technique is presented for obtaining vehicle frontal crush characteristics from a series of repeated low speed barrier crashes. Results were analyzed using a technique of linear correlation of residual crush depth with a defined crush energy parameter. The data compared closely with crashes reported in the literature, and suggested that the structure exhibits only a slight strain rate sensitivity. Crush energy is shown to correlate well with dynamic crush depth. Relations among dynamic and residual crush and recovery distance are reported, Velocity restitution is shown to be about constant at 15% over the impact velocity range employed. A force-deflection relation based on the offset force linear harmonic oscillator theory is suggested, shown to agree quite well with data. Repeated crash testing can be an effective method to obtain information needed for development of analytical and predictive tools useful in design and reconstruction.
Technical Paper

A Perspective on Automobile Crash Fires

1985-02-25
850092
The relatively rare occurrence of injury or fatality in fuel-fed fires has received considerable attention in automotive safety rulemaking and products liability litigation. The literature related to fatalities associated with fire is confirmed by recent FARS data, and there are no reliable field data which confirm a need for further injury-reducing effect related to FMVSS 301. NHTSA has acknowledged this by removing crash fire rulemaking from its priorities plan. The police-reported crash fire data now available must be supplemented with in-depth investigation by trained teams before informed judgements can be made regarding further safety improvements with respect to crash fire injury.
Technical Paper

Inaccuracies in the CRASHS Program

1985-02-25
850255
The CRASH3 computer program, a well known and useful tool in accident reconstruction, is shown to be innaccurate by comparison with car-to-car crash test data. Claims for accuracy of about 10 percent cannot be validated. Both the impact model and the damage only model yield results which are in error. Cases involving error well in excess of 20 percent are demonstrated. These inaccuracies are due primarily to the omission of terms in the formulation of the energy equation and to the sensitivity of the solution to the input estimate of principle-direction-of-force.
Technical Paper

Design, Development and Testing of a Load-Sensing Crash Dummy Face

1984-02-01
840397
This project covers one facet of a program to develop a mechanical model for characterizing the time history of local forces on the zygomatic, maxillary and mandible regions of the human face during a frontal collision. Two mechanical devices to measure the forces on crash dummies during testing were designed, constructed and tested. The devices employed cantilever beams equipped with strain gauges. Both devices were subjected to a series of drop tests onto various materials. Time histories were compared to those obtained from cadaver experiments. While the data obtained from this testing appears to be similar to the cadaver data, further improvements and modifications will make the model much more useful.
Technical Paper

Improvements to the SMAC Program

1983-02-01
830610
The Simulation Model of Automobile Collisions (SMAC) computer program has seen more than a decade of use under NHTSA auspices. Although SMAC has proven itself to be a useful investigative tool, the program has several shortcomings which either have been addressed by the authors or need to be addressed by further work. This paper presents the results of our ongoing work to improve SMAC and our recommendations for further work. Those model features discussed herein which either have been or need to be revised consist of (1) the calculation of crush forces when penetration is deep (2) the representation of the vehicles' crush pressure vs deflection relationship and (3) the distribution of tire normal forces in reaction to pitch and roll. An input interfacing program called SMACED has been written and is discribed. This editing program greatly simplifies the use of SMAC and will be found particularly useful for the inexperienced or infrequent SMAC user.
Technical Paper

Interrelationship of Velocity and Chest Compression in Blunt Thoracic Impact to Swine

1981-10-01
811016
As part of a continuing study of thoracic injury resulting from blunt frontal loading, the interrelationship of velocity and chest compression was investigated in a series of animal experiments. Anesthetized male swine were suspended in their natural posture and subjected to midsternal, ventrodorsad impact. Twelve animals were struck at a velocity of 14.5 ± 0.9 m/s and experienced a controlled thoracic compression of either 15, 19, or 24%. Six others were impacted at 9.7 ± 1.3 m/s with a greater mean compression of 27%. For the 14.5 m/s exposures the severity of trauma increased with increasing compression, ranging from minor to fatal. Injuries included skeletal fractures, pulmonary contusions, and cardiovascular ruptures leading to tamponade and hemothorax. Serious cardiac arrhythmias also occurred, including one case of lethal ventricular fibrillation. The 9.7 m/s exposures produced mainly pulmonary contusion, ranging in severity from moderate to critical.
Technical Paper

Thoracic Impact Response of Live Porcine Subjects

1976-02-01
760823
Five anesthetized porcine subjects were exposed to blunt thoracic impact using a 21 kg mass with a flat contact surface traveling at 3.0 to 12.2 m/s. The experiments were conducted to assess the appropriateness of studying in vivo mechanical and physiological response to thoracic impact in a porcine animal model. A comprehensive review of comparative anatomy between the pig and man indicates that the cardiovascular, respiratory and thoracic skeletal systems of the pig are anatomically and functionally a good parallel of similar structures in man. Thoracic anthropometry measurements document that the chest of a 50 to 60 kg pig is similar to the 50th percentile adult male human, but is narrower and deeper. Peak applied force and chest deflection are in good agreement between the animal's responses and similar impact severity data on fresh cadavers.
Technical Paper

An Inexpensive Automobile Crash Recorder

1974-02-01
740567
One of the greatest challenges faced in the design of realistic occupant protection systems is an accurate statistical model of what is really needed. The paucity of data is this realm hinders designers of standards alike. Ideally, a model of crash statistics would correlate, for significant accident modes, injury level (as measured by AMA Abreviated Injury Scale “AIS”) with some adequate measure of crash intensity. Having this information, not only could the required level of safety design be ascertained, but also the justifiable economic expenditure could be estimated. This paper treats the statistical basis for deployment of a data retrival system. It provides a basis for estimates of the amount of data required, the number of vehicles to be instrumented, the crash severity trigger levels, and the economics of recorder installation, for various levels of injury and fatality.
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